United States Department of Agriculture researchers have put 173 tomato varieties to a taste test to help breeders develop more flavorful fruit.

Using the Tomato Germplasm Collection in Geneva, the Agricultural Research Service (ARS) and North Carolina State University selected a cross section of tomatoes to represent the fruit’s global diversity.

The varieties were planted on test plots in North Carolina and examined for ratios of sugars, organic acids, and volatile compounds derived from amino acids, lipids and carotenoid precursors.

By analyzing such compounds, the team hoped to pinpoint the qualities that create an ideal, garden-fresh taste, explained ARS molecular biologist Joanne Labate.

“Commercial tomato varieties have a narrow genetic base. To find ways to improve their flavor, we need to broaden that base and begin looking among our entire stock of tomatoes for new sources of beneficial genes,” Labate said.

The test tomatoes were placed in three categories: plum or roma, cherry or grape, or the traditional large, round types. After, they were ranked on a scale of 1 to 5 on odor, taste, flavor and texture by volunteer taste testers.

Although thousands of compounds play a role in tomato development, sugar and acid were found to play a key role in overall flavor.

“While the amount of acid varied only slightly in the tomatoes tested (from 0.2 to 0.64 percent), there was a wide variety in sugar content (3.4 to 9.0 percent). That’s important because, for ripe tomatoes, the greater the ratio of sugar to acid, the sweeter the tomato. The sweeter the tomato, the more flavor it contained,” ARS reported.

“The growing environment will affect the expressed traits, but being able to identify and select superior tomatoes for breeding might increase the frequency of favorable alleles being transferred into different varieties and ultimately improving them,” Robertson said.

The study was published in Plant Genetic Resources: Characterization and Utilization.